Sunday, January 21, 2007

Coronary Calcium Screening by CT Scan

New guidelines by the American Heart Association and the American College of Cardiology were issued earlier this week supporting the use of coronary calcium scans to assess risk of future heart attack.

Coronary calcium scans, also known as heart scans, provide pictures of the calcium deposits in coronary arteries that might herald the existence of a significant blockage. Depending on the amount of calcium detected, the result of this test is often called a coronary calcium score. Scores range from 0 to over 1000, with the lowest numbers suggesting lower risk and higher numbers suggesting a higher risk of future heart attack. Heart scans and coronary calcium scoring may indicate if someone is at a higher risk of a heart attack or other problems well before they have any outward symptoms of disease.

The new guidelines represent a reversal of the AHA/ACC recommendations from 2000 when there were insufficient data to formalize recommendations regarding coronary artery calcium (CAC) screening to the general public.

But the new recommendations, published online 12 Jan 2007 in the online version of the Journal of the American College of Cardiology, are made with some qualifications. CAC screening is only recommended for patients at moderate risk of developing coronary artery disease while very high and low risk patients are still not recommended to have CAC screening.

So what justifies a moderate-risked individual in whom the CAC screening is recommended?

People referred for CAC screening should not have evidence of other vascular disease or be at high risk of developing such disease (like diabetics or those with known coronary artery disease). If a person has a greater than 10% risk of cardiovascular death in 10 years as determined by having two or more of the following cardiovascular risk factors: cigarette smoking, hypertension exceeding 139/89 or those being treated for hypertension, high cholesterol or low HDL (< 40 mg/dl), a family history of premature coronary heart disease (male first-degree relative < 55 years or a female first-degree relative < 65 years) and age (men >45 and women >55), then they might be candidates for screening.

You can estimate your own risk by using this special calculator from the National Heart, Lung, and Blood Institute.

People with 0 to 1 of the cardiovascular risk factors above should not undergo screening, according to the guidelines.

The controversies and limitations of this test are nicely outlined here. Realize, too, that this report does not cover the appropriateness of newer, 64-slice CT scanners for evaluation of coronary artery disease screening. (Medicare still considers these "experimental").

So look for more CT scanners to come to a mall near you - but only get it if you really need it.


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